Defects/vacancies engineering and ferromagnetic behavior in pure ZnO and ZnO doped with Co nanoparticles

Abstract Nanoparticles (NPs) of undoped and Co (10%) doped ZnO were synthesized through auto-combustion route. XRD patterns confirm the single phase nature and the incorporation of Co 2+ ions into ZnO matrix. The average crystallite sizes were ⿼22.1 and ⿼14.6 nm for undoped and Co doped ZnO respectively. Native defects/vacancies create energy deep-levels (EDLs) in the band gap region that have been studied through photoluminescence (PL) spectroscopic. The donor band nature of Vo is ⿼0.79 eV above valance band maximum (VBM). VBM and electronic structure have been evaluated via X-ray photoelectron spectroscopy (XPS). Undoped and Co doped ZnO NPs show ferromagnetic (FM) behavior. The weak FM in Co doped ZnO can be elucidated by bound magnetic polarons (BMPs) mechanism. Zinc vacancies (V Zn ) seem to be the responsible for d 0 ferromagnetism in pure ZnO NPs. We aim to correlate the FM ordering with the native defects concentrated at the surface of NPs.